MPEG (Moving Picture Coding Experts Group) 4 and similar multi-media encoding systems (hereinafter referred to as MPEG-4) having a similar intellectual property rights (ex., copyright) management and protection system (IPMP system) are receiving much attention in the movie industry and other fields which place much importance on protection of copyrights. This is because such encoding systems have a system for protection of copyrights within the contents itself.
FIG. 1 is a schematic diagram of an MPEG-4 player explaining a copyright protection system of the MPEG-4. FIG. 1 was drafted based on “ISO/IEC 14496-1 FIG. 8”, and detailed explanation thereof is abbreviated here.
As depicted in FIG. 1, an IPMP system 102 obtains information relating to copyright protection via an IPMP decode buffer 101, and processes this information. The IPMP system 102 is configured so as to be able to reference an object descriptor (OD) 103 while performing such operations as decoding code of each object such as voice or picture images and detecting digital watermarks.
On the other hand, specific commands regarding the decoding of the code and the detecting of the watermark, such as what sort of technique should be applied and what part should be processed, are generally written among the data read by the IPMP system 102 as the IPMP stream. In other words, the IPMP system 102 must be designed in advance so as to be able to interpret the contents of the IPMP stream.
The most important part of the IPMP stream, the IPMP message, is described in “ISO/IEC 14496-1 8.3.2.5 IPMP message syntax and semantics” as follows:
8.3.2.5.1 Syntaxclass IPMP_Message( ) extends ExpandableBaseClass{bit(16) IPMPS_Type;if(IPMPS_Type == 0){bit(8) URLString[sizeOfInstance-2];} else {bit(8)IPMP_data[sizeOfInstance-2];}}8.3.2.5.2 SemanticsThe IPMP_Message conveys control information for an IPMP System. IPMPS_Type—the type of the IPMP System. A zero value does not correspond to an IPMP System, but indicates the presence of a URL. A Registration Authority as designated by the ISO shall assign valid values for this field.URLString[ ]—contains a UTF-8[3] encoded URL that shall point to the location of a remote IPMP_Message whose IPMP_data shall be used in place of locally provided data.IPMP_data—opaque data to control the IPMP System.
What is important here is that the IPMP system type (IPMPS_Type) can uniquely identify the specifications of the data, being the main part of the IPMP stream, and that the contents of the data portion (IPMP_data) are not particularly determined.
That is, it is presumed that the contents formation system can understand the IPMP system used by a contents reproducing device (such as a player), and the IPMP message must be buried into the multi-media data which is the contents.
Further, from the perspective of the contents reproducing device (i.e., the player), it is necessary to examine the IPMP system type (IPMPS_Type) in order to determine whether it will be possible to interpret the IPMP message in the multi-media data that the player will attempt to reproduce.
Thus, in the prior art, in order to transfer IPMP data that could be understood by both the contents formation system and the reproducing device in advance, one had to use IPMP system type as one's sole starting point.
As described above, in the conventional MPEG-4 and conventional contents formation systems and contents reproducing devices having intellectual property rights management and protection systems (i.e., IPMP systems) similar to MPEG-4 for use in multi-media encoding systems similar to MPEG-4, the means for verifying the IPMP data for activating the intellectual property rights (ex., copyright) protection system relied solely on the IPMP system type (IPMPS_Type). Thus, there existed the following problems.
(1) In the case that an IPMP message defined in a specific IPMP system type is read by an ill-intentioned external third party, the IPMP message may be switched over to a new protection system. However, in order to use a message of the new protection system, it is necessary to register the new IPMP system type with the RA (registration authority), even if the change is minimal. It is also necessary to establish an IPMP system having a different IPMP system type from the previous IPMP system type and an IPMP system that can interpret the IPMP stream. As a result, the contents formation system and the contents reproducing device needs a redundant process recognizing multiple IPMP system types registered with the RA, and thus, decreases in processing efficiency and increases in memory usage may occur.
(2) Also, in the process of upgrading, in a case where the IPMP system type remains the same while the IPMP stream is generated with partially-different data specifications, since the IPMP system type is the only reference for the contents reproducing device for verifying whether the IPMP message can be interpreted or not, the IPMP system type is no longer identifiable uniquely. Thus, inconvenient runaway processing may occur.
(3) Even when the IPMP system of the contents reproducing device responds correctly to the sent IPMP message, there can still be instances in which the IPMP system cannot operate properly. In this case, there is no way for the contents reproducing device to inform the side that sent the contents that the IPMP system did not operate properly.
(4) For example, there are instances in which it is presumed that the side sending the contents will convert the contents into an IPMP message of an IPMP system type that the contents reproducing device corresponds to, and then send the contents. However, in such instances, the contents-sending side cannot provide instruction as to when the contents reproducing device should give notification of the IPMP system type that the contents reproducing device corresponds to.
(5) The IPMP message is one stream buried into the contents; therefore, in the case when no contents exist, it is impossible to perform a test or tests of conditions by means of standard technique based on the MPEG-4. Also, there is no method available for testing the IPMP during reproduction in a way that does not influence the reproduction. Thus, there exists no test method that is standard across different devices, and there is no chance of guaranteeing compatibility across the respective devices.
(6) Related to the above problems, it is impossible to request a communication path protected by security technology from the contents reproducing device to a so-called “back channel” of the side sending the contents.
The above-mentioned problems are based on the need in an IPMP system to guarantee unique identifiability and to guarantee security such that details of such the indentificability are not generally disclosed. This unique identifiability and this security rely on the contents forming device and method, and the operation of the contents reproducing device and method. In the prior art, in order to resolve these problems, it was necessary to apply extremely complicated control systems. When these types of resolutions are applied to portable apparatus with limited processing power and memory, it is particularly difficult to avoid problems.
In light of the above-mentioned issues, an object of the present invention is to provide a contents forming method, a contents reproducing method, a contents reproducing device and a computer readable storage medium storing a program for executing the contents forming method or the contents reproducing method, being capable of performing more efficient processing by adding discrepancy (version) information or request information of IPMP data, in addition to the IPMP system type in the IPMP stream, in an encoding system of MPEG-4 with an IPMP system or an encoding system with an IPMP system that is similar to the MPEG-4.